Pilots are usually used in connection with counterbores. Counterbores are tools usually made of steel, with either carbide or ceramic inserts. They will have ground edges or edges with inserted cutting bits secured in a way as to cut readily as you apply pressure, usually in a vertical motion or motion opposite the cutting edge. Counterboring is usually a secondary operation proceeding a drilling operation. However, a drill insert could also be a counterbore. The job of the counterbore tool is to bore a flat bottom hole larger than the pilot or spot face with or without a chamfer. The counterbore currently used is a single or a multi-edged cutting tool that rotates about and uses a pilot to guide at the cutting edge end.
Usually, this pilot is either fixed, or built into the tool, or in some applications replaceable. The main problem with pilots is that they wear quickly in high volume manufacturing. When this happens, control of the center line of your geometry or spectrum is lost. Thus, one of the objectives of this invention is to create a pilot that has a longer wear life, especially in high volume manufacturing. Another problem is that when the pilot is built into the tool and gets worn to the point no one can no longer make an accurate location of the opening to the bore, you must dispose of the whole tool. Among other problems, the pilot tends to break off at the stem resulting in extra cost in accuracy and lost productivity. Thus, one of the objectives of this invention is to build a pilot that, when worn, can be replaced easily without causing the whole tool to be damaged.
The revolving pilot, however, can be used in connection with different cutting tools such as chamfers, radii etc. The revolving pilot can be used with any tool in which an implement is placed in an opening to maintain the position of the tool. The pilot can be designed to be used as a belting pilot drilled to fit in openings that are not yet drilled. Although the revolving pilot is usually on the end of the tool, it could also be used in the middle or other areas in order to maintain the tools position or alignment to bore when line boring; thus will be a revolving guide.
The feature that achieves these objectives are that the pilot is actually made of only five components. These components are replaceable, thus, if any one of the components wears out, one can easily replace the component and not have to throw out the whole tool. The component that usually wears the most and is replaced the most, is the bearing.